Santana said he heard the sound of a Taser being deployed and Scott began running before the shots were fired.

He began recording when he heard the sound of a Taser. "Mr. Scott was trying just to get away from the Taser," Fayden Santana said.

The video then shows Slager firing eight times at the back of the unarmed man, until he crumples to the ground about 30 feet away.

Santana said Scott appeared to have already been unconscious when the officer put handcuffs on him and walked away.

Santana turned the video over to Scott's family and has been cooperating with investigators.

Santana told MSNBC that he initially considered deleting the video, and thought about leaving North Charleston out of fear for his own safety.

Santana, a barber originally from the Dominican Republic, said he later saw a police report about the shooting and knew that he had to come forward because the officer's account of what led to the shooting didn't match what he recorded.

Santana said he showed the video to a friend after reading the report, and his friend agreed that he needed to come forward.

"I just put myself in the position of the family," Santana said, adding that he knew no charges would be filed against the officer who shot Scott if the video wasn't released.

The family's lawyer, L. Chris Stewart, calls Santana a "hero."

Santana, who has been cooperating with investigators, acknowledged that "the officer also has his family."

"But I think that he made a bad decision. And you pay for your decisions in this life, I think," Santana said.